brooklyn



Patented Sept. 25, 1923.

UNITED STA'i'iiL PATENT OFFICE.

FRANK JOSEPH CBUPI, OF BROOKLYN, NEXV YORK, ASSIGNOR TO HERMAN BEHR & 00., INCL, OF BROOKLYN, NEW YORK, A CORPORATION 01 NEW YOBK.

METHOD OF MAKING ABRASIVE ARTICLES OF MANUFACTURE AND PRODUCT.

No Drawing.

T 0 all whom it may concern:

Be it known that I, FRANK JOSEPH CRUPI, a subject of the King of Italy, and resident of Brooklyn, in the county of Kings and State of New York, U. S. A., have invented certain new and useful Methods of Making Abrasive Articles of Manufacture and Product, of which the following is a specitication.

This invention relates to a method of making abrasive articles of manufacture and product, such as abrasive sheets, discs, belts, wheels and the like, in which abrasive material is held on a backing of any suitable material. The backing is usually some appropriate fabric, such as paper or cloth or a combination of both, and for several years past there has been a growing demand for an abrasive material or cloth which is sufficiently waterproof to withstand disintegration when used on wet surfaces. This de mand has become very extensive among fin-- ishers of painted or varnished surfaces where ordinary dry sandpapering is exceedingly unhealthful due to the poisonous nature of particles dislodged from the surfaces abraded. Many workmen who have inhaled such dust or other dislodged parti cles for considerable periods have suffered injuries and diseases of the lungs.

An object of my invention is to produce a wateroroof abrasive article of manufacture adapted to withstand disintegration when used on wet surfaces, and constructed to hold both line grade abrasive material and coarse grade abrasive material in place on. the backing.

Heretofore, in using so called sandpaper-s, wetting of the abrasive and abraded surfaces has proved advantageous, not only because of the laying of the dust, but also because of the resultant effect of a better finish. However, ordinary sandpaper rapidly disintegrates when used on wet surfaces, and this disintegration of the material has always been objectionable. It is for these reasons that the extensive, demand for waterproof sandpaper has arisen among sandpaper mani'ifaetnrers, health brreaus and workmen.

Serial No. 589,942.

For many years nothing could be found which was suiiiciently waterproof and at the same time practical for holding both small and large grains of abrasives in place, though many attempts have been made so to do by the use of various compositions, comprising rubber, varnishes, gums, waxes, cellulose compounds, oils, etc.

So far as I am advised no composition has been found prior to my invention whereby the coarser grains of abrasive can be properly held in a waterproof abrasive manufacture. However excellent the results of the kind in question have been with finer grains of abrasive, it is still true that great numbers of workmen who require coarse grain sandpapers are unprovided with waterproof, coarse grain sandpaper-s, for which the demand is insistent.

In the attempt to solve the serious and difficult problem above indicated, I have covered a wide field of. research and made great numbers of experiments which have resulted in fine and coarse grain waterproof sandpapers that have been subjected to actual uses under workin conditions and appear to solve the problem.

I have, prior to this invention, invented and used a flexible, water-resisting cement for the purpose of holding abrasives in place on backings, and made in accordance with the following formula:

Rosin "about 250 lbs. avoirdupois Glue 11 n n 87% phenol (carbolic acid) 100 33% acetic acid--- 200 In continuation of the work done under the above formula, I have constantly borne in mind the practical requirements of the art; that the product in question should be waterproof, cheap, tough and flexible, and preferably capable of being used with present manufacturing equipments. And I have recognized the difficulty with most compositions proposed in the prior art, that while some of them were waterproof they lacked flexibility and toughness, and therefore could not hold the abrasive, while others were very tough and flexible but Rosin 250 lbs. avoirdupois 87% phenol (carbolic acid) Glue (i0 Water 56% ace 1c Benzlne or benzene 5 in preparing the above compositions the full quantity ol rosin in powdered form is placed in a copper tanlc 'u 'hich is jacketed and equipped with a heating device. The phenol is then poured into the rosin and mixed well with it, the resin being soluble in phenol. Alter allowing the phenol and rosin to soak for a short time, the heat is turned on in order to dissolve the resin thoroughly, whereupon both ingredients react to form a rosin ester, in which case the resin probably acts like an acid and the phenol like an alcohol- This solution will absorb a limited amount of water. 7

In a separate container, l prepare a solution of glue, which is preferably hide glue, wi ththe water and acetic acil specified in the formula. The glue is easily dissolved in the acetic acid and water volume by the aid of little heat, and when so dissolved is poured into the solution oi phenol and rosin, accon' panied by constant and rapid stirring.

The glue, acetic acid and water solution mixes with the resin and phenol solution and upon coming in contact with the excess of phenol, over and above the phenol required to unite with the resin, the glue is in'unediately reacted upon by the phenol and would coagulate were it not for the excess of the acids present which tend to reverse or prevent the coagulation. This combined n'iirtureott the rosin solution and of the glue, water and acetic-acid solution is insoluble to some extent in water, but it will absorb a limited amount oi water and thicken very heavily, due to hydration of the colloids.

The carbolic acid in the mixture serves to reduce the surface tension between the glue and the rosin and. causes a more thorough intermixture or emulsion oi. the whole colloidal system.

Now a solution of resin, grlue and phenol alone if spread on paper would take a long time o dry. and is not entirely satisfactory .ramilieation on backingzs. It is desirable to use the lean amount of phenol that is practicable because an unnecessary eXcess only serves as a detriment to dryingand is, moreover, undesirably expensive. ilonsequently, in economic practice, it is actually a heavy or thick mixture that formed, and such mixture requires a diluent.

l. find thatwater is very objectionable as a diluent in this case because it thickens or raises the viscosity and also so affects the surface tension condition of the colloidal system. as to impair its waterproof qualities.

A nd 1 have found that T can use acetic acid having a water content as diluent because the presence of this acid tends to iniprr re the surtace ension condition and to keep the glue fro" Eellying while it is being spread.

' As the colloidal V 7 mixture of resin, glue, phenol, acid. and water, the union or intermixture o? bothv phases, water-soluble and water-insol uble, is quite homogeneous and could be used with satisfaction, but l have found that the addition oi small. amount otbensine (5 lbs.) still further improvesthe composition, in that it increases waterproof qualities without ap eciaoly diminish ng the toughness and lielne This is due o tl l ty. lowing;- changein e colloidal s stem... Without the benzinmthe water e phase, that is the rosin phase, is more the dispersed phase, that the glue phase, so tha there exists in the colloidal solution. particles of glue and particles of rosin minutely SllDCllvided and intermied. The glue particles, for the greater part, form the continuous phase and envelop the rosin particles. The greater the extent to which this condition is brought about, which can be done by add ng excessive nounts of the wateesol uble phase. or anything which will. lower the tension of the w. ;er-seluhle phase, the tougher or stronger the dried lay-- er of the solution will be but the lower in waterproof qualities. ii. on the other hand, the surface tension relations are raised, which can be done by adding); excessive amounts of the water-insoluble phase or ben-- iiine, the condition will be reversed, i. e.,

sui race the rosin particles, on account of the presonce of the benzinc, gain the upper hand and "elop the glue particles. the colloidal sys tem then forming particles of glue as the dispersed phase surrounded by par icles of rosin as the contiuous phase.

The resulting solution, when dry, is very waterproot, but not tough or flexible. So. briefly, it seems that when the glue phase predominates it envelopes the resin part'cles and naturallylhe glue being able to unite thoroughly throughout would dry very strong, but being exposed, since the resin particles are on the inside, it is not very waterproof; and vice versa when the resin phase predominates.

system exists new in this In order to bring about the most homogeneous distribution of both phases, I have found that only a small amount of benzine such I use in my formula, will, in this composition, serve beneficially to that end, the resulting product being a colloida systern homogeneous throughout with about as many glue particles surrounding rosin particles as'rosin particles surrounding; glue particles; and the result is wate o tough and flexible qualities.

To return to the acetic acid again, were I to eliminate it, or eliminate it beyond a limited extent, I would be confronted with the following phenomena. The solution upon being applied on, the paper would im mediately jell. which fact would cause an aggregation of the minute colloidal. particles. In this stiffened condition, the more force of spreading would break the globules open so to speak. These would immediately set and harden in that condition without any of the beneficial colloidal homogeneity properties functioning.

The presence of acetic acid, on the other hand, keeps the solution fluid and homogeneous throughout, so that afte the force exerted on the mass in spreading it has been removed, the solution will regain its origi nal characteristics and dry accordingly. Therefore, it is obvious that each and every one of my ingredients has a specified importance in this composition.

To conclude, the whole solution as I have F formulated and described it, is very stable and can be used at any time after being prepared. It will retain its chemical and physical properties, being a fluid while hot and jelly when cold.

This solution as it is, can be used alone and be quite satisfactory, but I have found that a formaldehyde treatment, and finally a very thin coat of linseed oil. rill improve the qualities of the finished product con siderably.

The process of manufacturing the water proof paper, which I have found to be eutirely successful, is as follows:

It has been found in the manual use of a' waterproof abrasive paper on wet surfaces, that the back needs to be waterproof well as the front. since the paper upon becoming wet will wear through very easily, due to the friction of the hand or fingers on the baclr of the paper with which it was being: held. Therefore, the backof the paper is primarily coated with any cheap waterproofing compound that when wet will re sist the pressure and friction of the fin gers. For this purpose i have utilized a well-lrnown reaction of glue with formaldehyde. This is done as follows:

The paper is passed through coatino machine, which applies a coating: of glue solution. While the glue on the paper is not yet entirely dry it is treated with a diluted solution of formaldehyde. This formaldehyde combines with the glue and the re sulting dry layer forms a water-insoluble protection for the backing of the paper.

On account of its strep h, and flexibility and convenience of making, I would rather use such material than was, oil or varnish compositions.

After the back of the paper is so treated, it is passed through a coating-machine where it receives the usual coating of glue. Immediately following, is sprinkled into the layer of glue which is yet warm and plastic, the usual coating of abrasive material. The paper then travels along racks into a sizing machine. Here, instead of being: sized with ordinary glue solution, it is sized with said water *oofing solution which is immediately sprayed with a diluted formaldehyde solution.

The water-resistant composition enters the interspaces between the abrasive grains and its solvent action on glue causes it to unite with the underlying glue coat which primarily held the abrasive grains in place; and the united water-resistant composition and glue set as a tough, flexible. water-resistant binder or bond which holds the abrasive gains in place.

The purpose and advantage of spraying this water-resistant composition with a solution of formaldehyde are as follows:

The composition consists of two collodial phases-the rosin phase and the glue phase. It is to be remembered that there exist glue particles which are exposed although not freely exposed. I have found that a piece of sandpaper made with this composition. but without the formaldehyde treatment, although it will last to a certain degree of satisfaction. the glue phase being not as water-resistingas the rosin phase, will begin to wear out under the strain of the friction and water. Such removal of the glue particles leaves an open framework or porous structure of rosin particles, which alone cannot stand the furl'l r tension of friction, and rapidly disintegrate. So it being known that formaldehyde renders clue insoluble though not impervious, I thought of the following treatment which overcomes this condition. Although the glue pan-Jicles of the solution are perhaps softened due to a slight absorption of water, still they do not dissolve or wear out very easily, and consequently the whole waterproof structu e able to retain its lastino qualities.

iinother advantage of this formaldehyde treatment that unorimmediately spraying r treatingotherwise mv waterproofing com sitiou with formaldehyde. the formaldc do quickly reacts on the glue phase of t collodial composition and sets it sti'lfens it so that it imprisons some of the solvents ing; in coating the glue and abrasive coat waterproof and tough composition that holds the abrasive elements in place,

The product is then again dried and is ready to be used, the resulting product being a satisfactory, waterproof sandpaper possessing all the necessary qualities and being practically the first of its kind, and the only one yet made, so far as known, which lills' all requirements of the trade. 7

g It will be observed that the actual water content of each of the two formulas above specified is very nearly alike. 7 7

The product smells of carbolic acid and if the benzine and linseed oil solution is used as a final sizing, the product is further characterized by an oil film, in addition, of course, to solids. I

What I claim is:

1. i The herein described method of making abrasive manufactures consisting in coatinga backing with a solution of glue; in applying abrasive material to the glue coating; in coating the glue and abrasive coating with a colloidal, waterproof, adhesive composition containing rosin, glue, phenol, acetic acid and water in about the proportions stated, and in which the acids prevent coagulation of the glue.

2. The herein described method of'making abrasive manufactures consisting in coating a backing with a solution of glue; in applying abrasive material to the glue coatin with a colloidal water aroof adhesive composition containing rosin, glue, phenol, acetic acid and water in about the proportions stated, and in which the acids prevent coagulation of the glue; and in spraying the so formed abrasive surface of. the web with a formaldehyde solution.

3. The herein described method of malting abrasive manufactures consisting in coating a backing with a solution of glue; in applying abrasive material to the glue coating; in coating the glue and abrasive coating with a colloidal, waterproof, adhesive composition containing rosin, glue, phenol, acetic acid and water in about the proportions stated, and in which the acids prevent coagulation of'the glue; and in sprayingthe so formed abrasive surface of the web with a formaldehyde solution; and in drybasic ing the web thus treated'and then sizing the abrasive surface with a solution of boiled linseed 011 in benzene.

4:. The herein described method of making abrasive manufactures consisting in coat ing a backing with a solution of glue which primarily holds the abrasive material in place; in applying abrasive material to the glue coating; coating with a compound of rosin, glue, an acid having a water content and benzine.

5. The herein described method of making abrasive manufactures consisting in with a solution of glue coating a backing which primarily holds the alnrasivematerial in place; in applying abrasive material to" the glue coatin sive coating with a compound of resin, glue,

an acid having a water content and benzine; and in coating the surface thus formed with a 10% solution of boiled linseed oil in benzine. V

7. The herein described method of making abrasive manufactures consisting in coating a backing with a solution of glue; in applyin g abrasive material to the glue coating; in coating the glue and abrasive coating with a colloidal, waterproof, adhesive composition containing rosin, glue, phenol, acetic acid and water in about the proportions stated, and in which the acids prevent coag ulation of the glue and the acetic acid and phenol act'as a solvent of the underlying glue for bonding the composition thereto; and in which glue particles are caused tobe surrounded by rosin particles and rosin particles are caused to be surrounded by glue particles; and in coating such surface with an oil film.

8.. The herein described method of making abrasive manufactures consisting in' coating a backing with a solution of glue; in applying, abrasive material tothe glue coating; in coating the glue andabrasive coating with a colloidal, waterproof, adhesive composition containing rosin, glue,phenol,

acetic acid and water in about the proportions stated, and in which the acids prevent coagulation of the glue; and in applying a glue coating to the back of the backing in sizing the glue and abrasive and while such. glue coating is moist in sizing the same with a formaldehyde solution. 9. As a new article of manufacture for subsequent use when dry a backing coated with a solution of lue and abrasive material; over the glue and abrasive material a coating containing rosin, glue, phenol, acetic acid and water, and in which the acids prevent coagulation of the glue and the acetic acid and phenol act as a solvent of the underlying glue for bonding the composition thereto.

10. As a new article of manufacture, a backing provided on one surface with a coating of glue, a layer of abrasive material on the glue and on the abrasive surface a coating comprising rosin, glue and an acid content and in which the composition is bonded to the underlying glue that holds the abrasive material.

11. As a new article of manufacture, a backing provided on one surface with a coating of glue, a layer of'abrasive material on the glue and on the abrasive surface a coating comprising rosin, glue and an acid content and in which the composition is bonded to the underlying glue that holds the abrasive material; and over the composition coating an oil film.

12. The herein described method of making abrasive manufactures consisting in coating a backing with a solution of glue; in applying abrasive material to the glue coating; in coating the glue and abrasive coating with a colloidal, waterproof, adhesive composition containing rosin, glue, phenol, acetic acid and water and benzine in about the proportions stated, and in which the acids prevent coagulation of the glue; and in spraying the so formed abrasive surface of the web with a formaldehyde solution; and in coating the same with oil.

Signed at New York city in the county of New York and State of New York this 15 day of September A. 1922.

FRANK JOSEPH CRUPI. 

